Internet DRAFT - draft-halpern-forces-lfblibrary-vpn
draft-halpern-forces-lfblibrary-vpn
Network Working Group
Internet Draft J.Halpern
Expires: July 2007 Self
Huaiyuan Ma
Huawei Technologies Co., Ltd
January 16, 2007
A VPN Library for use with the ForCES Protocol and Model
draft-halpern-forces-lfblibrary-vpn--00
Status of this Memo
By submitting this Internet-Draft, each author represents that
any applicable patent or other IPR claims of which he or she is
aware have been or will be disclosed, and any of which he or she
becomes aware will be disclosed, in accordance with Section 6 of
BCP 79.
This document may only be posted in an Internet-Draft.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
This Internet-Draft will expire on July 16, 2007.
Abstract
The forwarding and Control Element Separation (ForCES) protocol
defines a standard communication and control mechanism through which
a Control Element (CE) can control the behavior of a Forwarding
Element (FE). That control is accomplished through manipulating
Halpern,Ma Expires July 16, 2007 [Page 1]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
attributes of Logical Function Blocks (LFBs), whose structure is
defined in a model RFC produced by the working group. In order to
build an actual solution based on this protocol, defining a set of
Logical Function Block definitions that can be instantiated by FEs
and controlled by CEs is welcome. A base library definition of LFBs
is already given in library [5]. VPN (Virtual Private Network)
services, as a kind of important services widely employed in Internet,
will certainly be implemented in routers using this protocol. This
document provides an initial set of VPN LFB definitions in
particular, a set of tunnel encapsulator and decapsulator LFBs. It is
anticipated that additional VPN-related LFB definitions like L2VPN,
L3VPN can be defined over time.
Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119.
Table of Contents
1. Introduction................................................3
2. Tunnel Definitions..........................................3
2.1. GRE Tunnel Definitions.................................3
3. Security Considerations.....................................11
4. Acknowledgments.............................................11
5. References..................................................11
5.1. Normative References...................................11
5.2. Informative References.................................12
Author's Addresses.............................................12
Intellectual Property Statement................................12
Disclaimer of Validity.........................................13
Copyright Statement............................................13
Acknowledgment.................................................13
Halpern,Ma Expires July 16, 2007 [Page 2]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
1. Introduction
In a solution using ForCES protocol, Control Elements (CEs) can
control the behavior of Forwarding Elements (FEs) through
manipulating attributes of Logical Function Blocks (LFBs). LFB's
structure and abstract semantics is defined in Model [6]. That
document also defines a single LFB Class for gaining access to FE
properties including the set of LFBs and their interconnection. A LFB
class is defined to manipulate the protocol properties of the FE in
the protocol [4].
In I-D draft [5], a set of LFBs which are necessary to implement
basic forwarding process are defined. This draft is intended to
define an initial set of LFBs for a kind of important Internet
service, Virtual Private Network (VPN). It is expected that other
VPN-related definitions will be developed over time.
2. Tunnel Definitions
2.1. GRE Tunnel Definitions
GRE tunnel specification and its extension are described in RFC 2784
and RFC 2890 respectively. A GRE tunnel is composed of three parts:
outer delivery header, followed by a GRE header which is followed by
a payload packet. The format of outer delivery header is determined
by the corresponding delivery protocol, IPv4 or IPv6. In GRE header,
there are two important optional fields: one is called GRE key which
is intended to be used for identifying an individual traffic flow
within a tunnel; the other is called Sequence Number, the Sequence
Number MUST be used by the receiver to establish the order in which
packets have been transmitted from the encapsulator to the receiver.
The intended use of the Sequence Field is to provide unreliable but
in-order delivery. The payload packet would be IPv4, IPv6 etc.
When forwarding an IP packet in a next-hop applicator LFB, the
matched FIB entry indicates the packet should be transmitted over a
GRE tunnel and a correct tunnel index can be found out in the FIB
entry. The original packet will be fed to GRE tunnel encapsulator
with tunnel index as meta-data together in the downstream forwarding
process. Tunnel index points to the correct tunnel entry in tunnel
configuration table which stores the information of each tunnel. Each
Halpern,Ma Expires July 16, 2007 [Page 3]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
tunnel entry maintains a management flag called "TunnelState"
indicating whether the current tunnel is administratively up.
GRE tunnel maintains a fragmentation permitted flag. Before
encapsulating a payload packet GRE tunnel encapsulator will check the
size of that payload packet against MTU. If the size of tunnelled
packet is larger than MTU and at this moment that fragmentation
permitted flag should be checked, if that flag is set, then chop the
original packet into small packets with appropriate size, otherwise,
send ICMP message to notify the appropriate receiver of some error.
If the delivery protocol is IPv4, then the format of outer delivery
header would be IPv4, otherwise, it would be IPv6.
Once a IP packet with GRE is produced from an output port from GRE
tunnel encapsulator, a meta-data called "NextHopReference" which
points to the index of correct FIB entry is accompanied at the same
time, that is, an alias entry pointing to the next-hop table so that
it can use the predetermined route to the tunnel end-point.
When a classifier LFB identifies the incoming packet is an IP packet
with GRE at the GRE tunnel exit point, it will feed that packet to
the GRE tunnel decapsulator, which will find out the correct tunnel
index which maintains a local VPN ID field, the GRE tunnel
decapsulator then strips off the outer delivery header and GRE header
and feed it to the forwarding-related LFB with local index ID as
meta-data indicating which VPN that payload packet belongs to.
The actual GRE tunnel LFB class is defined as below.
<LFBLibrary provides="GRE_Tunnel_LFB">
<load library="Base"/>
<dataTypeDefs>
<dataTypeDef>
<name>NextHopIndex</name>
<synopsis>
An index used by the next hop table.
Typically stored in and generated as metadata by
the longest-prefix-match LFB
</synopsis>
<typeRef>int32</typeRef>
Halpern,Ma Expires July 16, 2007 [Page 4]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
</dataTypeDef>
<dataTypeDef>
<name>VPNID</name>
<synopsis>
An ID used to provide context for
VPN specific Packet processing.
</synopsis>
<typeRef>int32</typeRef>
</dataTypeDef>
<dataTypeDef>
<name>GRETunnelTableType</name>
<synopsis>
GRE tunnel configuration table
Each table entry describes a single GRE tunnel.
The table Index is input meta-data for the encapsulator.
</synopsis>
<array type="variable-size">
<struct>
<element elementID="1">
<name>TunnelValid</name>
<synopsis>
It is enabled or disabled by FIB indicating whether the current tunnel is permitted to
be used in forwarding process.
</synopsis>
<typeRef>boolean</typeRef>
</element>
<element elementID="2">
<name>FragmentationPermitted</name>
<synopsis>
it indicates whether it permits fragmentation when the size of a packet exceeds
the tunnel's MTU.
</synopsis>
<typeRef>boolean</typeRef>
</element>
<element elementID="3">
<name>ChecksumNeeded</name>
<synopsis>
it indicates whether a checksum is needed.
</synopsis>
<typeRef>boolean</typeRef>
</element>
<element elementID="4">
Halpern,Ma Expires July 16, 2007 [Page 5]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
<name>PacketType</name>
...needs definition ...
... probably for decapsulator error checking? ...
</element>
<element elementID="5">
<name>SrcAddr</name>
<synopsis>
IP Address for local end of tunnel
</synopsis>
<typeRef>IPAddress</typeRef>
</element>
<element elementID="6">
<name>DstAddr</name>
<synopsis>
Address for remote End of Tunnel
</synopsis>
<typeRef>IPAddress</typeRef>
</element>
<element elementID="7">
<name>GREKey</name>
<synopsis>
Key for this specific GRE Tunnel
The presence of this element indicate this tunnel uses
keyed GRE format.
</synopsis>
<optional/>
<typeRef>int32</typeRef>
</element>
<element elementID="8">
<name>NextHopReference</name>
<synopsis>
Reference to the correct NextHopIndex
This points to a LPM where the next hop is maintained.
The information is put in the encapsulator meta-data.
</synopsis>
<alias>NextHopIndex</alias>
</element>
<element elementID="9">
<name>MTU</name>
<synopsis>
Maximum Transmit Unit Used in conjunction with the flags
to decide if large packets should be encapsulated, fragmented,
or errored.
</synopsis>
<typeRef>uint32</typeRef>
</element>
<element elementID="10">
Halpern,Ma Expires July 16, 2007 [Page 6]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
<name>LocalVPNID</name>
<synopsis>
VPN ID used by decapsulator as generated
meta-data
</synopsis>
<typeRef>VPNID</typeRef>
</element>
<element elementID="11">
<name>TunnelState</name>
<synopsis>
It indicates whether the current tunnel is administratively up or down.
</synopsis>
<typeRef>Boolean</typeRef>
</element>
<element elementID="12">
<name>SequencingNeeded</name>
<synopsis>
it indicates whether a sequence field to differentiate different traffic flows in a
tunnel is needed.
</synopsis>
<typeRef>boolean</typeRef>
</element>
<element elementID="13">
<name>SequenceNumber</name>
<synopsis>
a sequence field to differentiate different traffic flows in a tunnel.
</synopsis>
<optional/>
<typeRef>int32</typeRef>
</element>
<element elementID="14">
<name>Checksum</name>
<synopsis>
The Checksum field contains the IP (one's complement) checksum sum of the all the 16 bit
words in the GRE header and the payload packet.
</synopsis>
<optional/>
<typeRef>int16</typeRef>
</element>
</struct>
</array>
</dataTypeDef>
</dataTypeDefs>
Halpern,Ma Expires July 16, 2007 [Page 7]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
<LFBClassDefs>
<LFBClassDef LFBClassID="0x00010010">
<name>GRE_Encapsulator</name>
<synopsis>
It specifies how to encapsulate an IP packet so that it can be transmitted over GRE tunnel.
</synopsis>
<version>0.0</version>
<inputPorts>
<inputPort>
<name>PacketIn</name>
<synopsis>
Normal packet in.
</synopsis>
<expectation>
<frameExpected>
<ref>IPv4</ref>
<ref>IPv6</ref>
</frameExpected>
<metadataExpected>
<ref>Tunnel_Index</ref>
</metadataExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort>
<name>PacketOut</name>
<synopsis>
IP packet with GRE
</synopsis>
<product>
<frameProduced>
<ref> GREFrame </ref>
</frameProduced>
<metadataProduced>
<ref>NextHopReference</ref>
</metadataProduced>
</product>
</outputPort>
<outputPort>
<name>FailOutput</name>
<synopsis>
error prompt information to indicate whether some operations like fragmentation are
Halpern,Ma Expires July 16, 2007 [Page 8]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
permitted.
</synopsis>
<product>
<frameProduced>
<ref>taggedFrame</ref>
</frameProduced>
<metadataProduced>
<ref>errorid</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<attributes>
<attribute access="read-write" elementID="1">
<name>GRETunnelTable</name>
<synopsis>
Table of GRE Tunnels supported by this
encapsulator
</synopsis>
<typeRef>GRETunnelTableType</typeRef>
</attribute>
</attributes>
<description>
when fowarding a IP packet, a matching FIB entry has a GRE tunnel flag which indicates it
should be transmitted over a GRE tunnel, then according to the constrains, TTL, MTU,
fragmentation flag etc in the GRE tunnel entry to encapsulate a IP packet in its payload
part.
</description>
</LFBClassDef>
<LFBClassDef LFBClassID="0x00010011">
<name>GRE_Decapsulator</name>
<synopsis>
It specifies the procedure how to decapsulate a tunnelled packet.
</synopsis>
<version>0.0</version>
<inputPorts>
<inputPort>
<name>PacketIn</name>
<synopsis>
A IP packet with GRE.
</synopsis>
<expectation>
Halpern,Ma Expires July 16, 2007 [Page 9]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
<frameExpected>
<ref>GREFrame</ref>
</frameExpected>
</expectation>
</inputPort>
</inputPorts>
<outputPorts>
<outputPort>
<name>PacketOut</name>
<synopsis>
original packet output
</synopsis>
<product>
<frameProduced>
<ref>IPv4</ref>
<ref>IPv6</ref>
</frameProduced>
<metadataProduced>
<ref>LocalVPNID</ref>
</metadataProduced>
</product>
</outputPort>
<outputPort>
<name> FailOutput </name>
<synopsis>
error prompt information generated when a GRE packet cannot match a GRE tunnel
state
</synopsis>
<product>
<frameProduced>
<ref>taggedFrame</ref>
</frameProduced>
<metadataProduced>
<ref>errorid</ref>
</metadataProduced>
</product>
</outputPort>
</outputPorts>
<attributes>
<attribute access="read-write" elemendID="x">
<name>GRETunnelTable</name>
<synopsis>
Reference to the GRE Tunnel Table this decapsulator uses
Halpern,Ma Expires July 16, 2007 [Page 10]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
which is stored in the corresponding encapsulator.
</synopsis>
<alias>GRETunelTableType</alias>
</attribute>
</attributes>
<description>
Once the classifier has determined the content of an incoming packet is GRE, it will be fed
to a GRE decapsulator, which can achieve the local VPN ID to which the packet belongs and
strip off the outer IP header and GRE shim, at the same time, treat local VPN ID as meta-
data and then feed it and original packet to the down-stream LFBs.
</description>
</LFBClassDef>
</LFBClassDefs>
</LFBLibrary>
3. Security Considerations
These definitions if used by an FE to support ForCES create
manipulable entities on the FE, Manipulation of such objects can
produce almost unlimited effects on the FE. FEs should ensure that
only properly authenticated ForCES protocol participants are
performing such manipulations. Thus, largely, the security issues
with this protocol are defined in Protocol [2].
4. Acknowledgments
Thanks Zengjie,Kou for providing some comments.
5. References
5.1. Normative References
[1] Khosravi, et al. Requirements for Separation of IP Control and Forwarding,
RFC 3654, November 2003.
[2] L. Yang, et al. ForCES Architectural Framework, RFC 3746, April 2004.
Halpern,Ma Expires July 16, 2007 [Page 11]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
[3] Yang, L., Halpern, J., Gopal, R., DeKok, A., Haraszti, Z., and S. Blake,
"ForCES Forwarding Element Model", Feb. 2005.
[4] A. Doria, et al. ForCES Protocol Specification, draft-ietf- forces-
protocol-06.txt, December 2005.
[5] Joel M.Halpern, A base Library for use with the ForCES Protocol
and Model, draft-halpern-forces-lfblibrary-base-01.txt, March,
2006
[6] L.Yang, et al. ForCES Forwarding Element Model, draft-ietf-
forces-model-06.txt
5.2. Informative References
Author's Addresses
Joel M. Halpern
Self
P. O. Box 6049
Leesburg, VA 20178
US
Huanyuan Ma
Huawei Technologies Co., Ltd
mahuaiyuan@huawei.com
Zengjie Kou
Huawei Technologies Co., Ltd
kouzengjie@huawei.com
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
Halpern,Ma Expires July 16, 2007 [Page 12]
Internet-Draft draft-halpern-forces-lfblibrary-vpn--00.txt January 2007
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Halpern,Ma Expires July 16, 2007 [Page 13]
